Telephone system for central stations.



EATENTED FEB. 27, 1906.

IONS.

APPLICATION FILED APR. 16,1902.

UNITED STATES PATENT OFFICE.

GUSTAF LAMBERT, OF CHARLOTTENBURG, GERMANY.

TELEPHONE SYSTEM FOR CENTRAL STATIONS.

Specification of Letters Patent.

Patented Feb. 27, 1906.

Application filed April 16, 1902- Serial No. 103.123.

specification.

It is well known that in the installation of telephone central stationsof larger size it has frequently been found convenient to arrange thesubscriber-circuits in the central station in two or more groups for thepur ose of both saving in multiple jacks and cab es and also in order toobtain a high efiiciency of the central station. The subscribers are forthis purpose provided with a signal-lamp, and the terminalsof thesubscriber-stations are provided with a suitable key for calling u i thedifl'erent groups of the telephone centra station. In cities with two ormore telephone central stations of larger extent, where the majority ofconversations are held on the in-' tercomnnmication lines and only somany subscriber-circuits need to be arranged in the central station asare contained on a milltiple circuit, it is, however, convenient toarrange the subscriber connections in a group and to arrange theleading-off intercommunication connections in one or several separategroups, each subscriber being provided with signaling devices, thenumber of these signaling devices corresponding to the number of theother stations on the same system. Thus the signal of the subscriberindicates directly with what station he desires to be connected.

"The operator therefore does not need-to inquire; but it is onlynecessary to establish communication with the desired central station ofan intercommunication circuit which is not-busy; In consequence of thesmaller number of talking-circuits within the central station in thiscase a larger number of subscriber-circuitsmay be arranged in the firstgroup upon each operating-tablethan was ordinarily the case. In theother groups intended for the leading off intercommunication lines up tothousand circuits may be attended to by the operator.

This invention has reference partly to the last-mentioned arrangement ofthe lines in separate groups for subscribers and for intercommunicationlines, and it refers partly to a switching device particularly suitablefor this purpose and for the first-mentioned arrangement in groups ofsubscribers in general.

The system and device is shown on the accompanying drawings for a numberof four groups.

The subscriber-table a is provided with the speaking-key I), included onthe branch 0 of t 1e subscriber double circuit 0 d, the arrangementbeing such that by depressing the key b the branch 0 of the subscribercircuit is grounded. By this earth connection the circuit of the battery0 is closed through the electromagnet f, the armature g of theelectromagnet h, contact-piece 2, the conductor 0, and the key I). Thealarm apparatus of the subscriber-table may be arranged in series with acondenser, or it is provided with so large a resistance that the currentof the battery '6 does not actuate the electromagnets f and 19,respectively, included upon the conductors c and (1 while the telephoneis suspended from the hook 0' and the key I) re mains inoperative. Upondepressing the key I; the electromagnet 7 will attract the armature i,pivoted upon the stationary pin 11. The hook 7a, which is attached tothe armature t and is rotatable upon the shaft 12, re, volves the wheel1 and turns the arm m, con' nected therewith, so as to cause the latterto rest against the contact a, the holding-dog 4 preventing backwardmovement of Z. If the speaking subscriber desires to obtain a connectionwithin the group I, he allows the key I) to reassume its originalposition of rest, and he then takes his telephone off from the hook 0.the double circuit 0 d are connected with each other .by the medium ofthe subscribertable. This results in a series connection of the coils 89 of the electromagnct p, which is shown in full lines, with theelectromagnet f and upon the circuit of the battery 6, a cir cuit beingestablished from one terminal at the battery e through the armature t,the armature g, contact-piece z, .conductor 0, subscribers table,conductor d, the contact 5, the armature 3, and the coils S 9, t0 theother terminal of the battery e. Inasmuch as the electr'omagnet 1) has avery considerable number of convolutions with comparatively highresistance, while the electromagnet f has a small number of convolutionswith low resistance, the current thus "produced will be sufficient onlyto excite the first electromagnet 3 but it will refuse to excite thelatter elec- By this means the two branches of tromagnet. The armature gis attracted, it closes the contact 13, and thereby establishes ,a localcircuit from one terminal of the battery 0 through r, the contact 5, andthe armature t, the dotted con'volutions (6-7) of the electromagnet p,the armature g, the contact 13, the glow-lamp a in the group 1, contactn, arm m, and wheel l to the other ter minal of the battery.Simultaneously with the contact 13 the contact 2 is closed, and theelectromagnet f is shortcircuited by means of the circuit-closing pieceZ, which is con nected to the armature g and is insulated therefrom. Thelocal circuit which actuates the armature g and the signal-lamp uremains closcdfor a sufiicient length of time until the operator of thegroup I answers to the call by inserting the plug 12 into the jack w,even if the hook 0 should be depressed in-the meantime.

B inserting the plug 1) into the jack w the con uctor 9cis grounded,thereby closing the circuit of the battery e by way of theelectromagnets h and 1 arranged in shunt-circuit. The exciting of theelectromagnet h results in the interruption of the contacts 8 and 2,thereby cutting out in the first place one of the branches 0 of the twobranches 0 d of the double conductor of the speaking subscriber from theswitching device, besides the coils 6 7 with the lamp a are cut off fromthe battery c. When the electromagnet y is excited, the contact 5 isbroken in the first place, thus cutting off the coils 8 9 of theelectromagnet p from the branch (1. Then the extension 0 the armature 3pulls the dogs is and 4 away from the wheel I, thus releasing the latterand causing the armm to return to its initial position by the action ofits own weight. The short circuit with the electromagnet 7 establishedby the contacts 1 and 2 is for the purpose of preventing any furtherdisplacement of the arm 'm by pressure upon the key I) after thetelephone has been taken off the hook or in consequence of theconnection to earth which might be established upon the insertion of theplug into the jack w. If the speaking subscriber wishes to actuateanother of the signal-lamps which belong to his line in another group,it is only necessary to depress the key I) so many times as the numberof the desired group indicates.

What I claim, and desire to secure by Letters Patent of theUnited'States, is-

1. A telephone system comprisin two or more groups at the centralstation W ich the subscriber may call up directly and whenever desired,a loop-conductor connected to the telephone central station, one branchof the double conductor-line of the subscriber including anelectromagnet f at the station, a circuit-closing piecemactuated b saidelec-. tromagnet, so as to assume the cal ing or signaling position,another electromagnet pupon the other branch adapted to be put inconnection with the said circuit closing piece m, and a signal lamp uthe circuit of which is maintained closed b means of the connectionsbetween said e ectromagnet p and said circuit-closing piece until thecall is answered from the station, the said signal-lamp being arrangedin the answering group.

2. A telephone systemcom rising a loopconductor line connected to t ecentral station, an electromagnet p in one branch of said loop and anelectromagnetf on the other branch, a selective means actuated by saidelectromagnet f and means to short-circuit the electromagnet f by theactuation of the electromagnet p until tfie'call is answered.

3. In a telephone system, com rising a loop-conductor liueconnected to te central station, substantially as described, and an electromagnet f onone branch and an electromagnet p, a signal-lamp on the other branch inconnection with said electromagnet 0, an inquirylug c and twoelectromagnets h and g excite by inserting the said plug, the armatureof the electromagnet 7 cutting out the subscriber-circuit. of theelectromagnetsfand p from the signa' -lamp, while the armature of theelectromagnet'y causes the circuit-closing piece m to return to itsinitial position and disconnecting the electromagnet p from thesubscriber-circuit.

4. Telephone system including magnets p, f and circuit connections,substantially as described, in which the number of cbnvolutions and theresistances of the electromagnetsf and p are so calculated that thecircuit generated in the subscriber-table after taking the telephone offits hook, actuates the electro ma net p only, but not the electroma etf, an selective means operated by said e 'ectromagnets.

In witness whereof I have hereunto s' ed my name in the presence of twosubscri ing witnesses.

GUSTAF LAMBERT. Witnesses: I, WOLDEMAR HAURT,

HENRY HASPER.

